The present invention relates to a sound field controlling device capable of adjusting a sound field when a multi-channel sound is played.
Recently, users who install a sound system capable of playing a multi-channel sound in a living room or a listening room to enjoy contents such as movies and music in home have been increased. For example, when the users play a movie DVD by using the AV system, the multi-channel sounds are played from a plurality of speakers. Accordingly, the users watch the movie while feeling surrounding sounds from circumstances.
In the above-mentioned sound system, it is important to adjust a balance of each channel so as to accurately perform a localization of a sound image. A system for adjusting a sound volume or frequency characteristics by outputting test sounds from speakers respectively and measuring a sound field of a micro listening room in order to adjust the balance, has come into practical use. For example, the above-mentioned system is a YPAO (Yamaha Parametric Room Acoustic Optimizer, which is a trademark), and so on.
Patent Document 1 discloses a sound playing device and a stereo sound playing apparatus capable of adjusting a ratio of a direct sound and an effect sound simulating a reverberation of specific gathering facilities.    [Patent Document 1] JP-A-2002-374599
However, since a sound field is to simulate an echo of a sound in a virtual space, it is important to balance a reverberant of a listening room to form satisfactory the sound field. Specifically, when a sound of gathering facilities such as hall is simulated so as to add the simulated echo and the simulated sound is outputted from the listening room, the balance may be more important.
However, the listening room has generally a bad balance regarding the echo. For example, since the room has one side wall, a curtain, furniture, and the like, a condition of absorption of sound, a condition of a reflection, and a condition of making a standing wave may be different. Accordingly, the echo in the listening room may be easily unbalanced.
Accordingly, although the balance of the sound level of the sound from the speaker is adjusted, the unbalance of the reverberation still remains. Thus, there arises a problem that a sound field having a good balance can not be formed.
In addition, as mentioned above, because of a shape of the listening room and the existence of the furniture or the curtain, the listening room generally has a frequency characteristic not being flat. That is, a specific frequency is highlighted as an ordinary wave by the shape of the room, or the specific frequency is absorbed so as to be blurred by the curtain and the furniture.
However, when the frequency characteristic is adjusted by directly operating a frequency characteristic of an audio signal, there arises a problem that the frequency characteristic is substantially blurred. For example, when the frequency characteristic of the listening room has a big dip and the frequency characteristic is adjusted by setting a filter having a big peak in the frequency characteristic, the frequency characteristic of the sound field after setting the filter is a flat frequency characteristic. However, there arises a problem that the direct sound component may be unnatural and is substantially harsh to hear.
Accordingly, an object of the invention is to provide a sound field controlling device capable of adjusting an output balance of the reverberation effect sound and the frequency characteristic of the reverberation effect sound on the basis of the sound field circumstances in which a sound system playing the multi-channel sound is disposed.
In order to achieve the above object, according to the present invention, there is provided a sound field controlling device for supplying audio signals to a plurality of speakers provided in a space to form a sound field in the space, the device comprising:
a measuring unit which measures levels of indirect sounds, which are outputted from the speakers, reflected from a wall surface of the space, and reach a listening position respectively;
a reverberation applying unit which generates a reverberation simulation signal for reinforcing the indirect sounds on the basis of the audio signals; and
a reverberation balance adjusting unit which controls the level of the reverberation simulation signal and supplies the controlled reverberation simulation signal to the corresponding speakers on the basis of the levels of the indirect sounds outputted from the speakers so that respective synthesized levels of the indirect sounds and the reverberation simulation signal are balanced between the speakers.
In the above configuration, the measuring unit which measures the levels of the indirect sounds outputted from the plurality of the speakers. The level of the reverberation simulation signal is controlled on the basis of the level of the indirect sound so that a synthesized level between the indirect sound and the reverberation simulation signal is balanced at every speaker in the reverberation balance adjusting unit. Accordingly, unbalance of an indirect sound of a frequency characteristic of an interior in which the sound system is installed and a feeling of lack in an indirect sound may be naturally supplemented. For example, the low reverberation may be supplemented by increasing an output of the reverberation simulation signal with respect to the output of the reverberation effect sound installed in the direction having a low reverberation. Accordingly, in the invention, an output balance of the reverberation simulation signal for reinforcing the indirect sound may be supplemented on the basis of the sound field circumstances in which the sound system is disposed.
Preferably, the audio signals supplied to the plurality of speakers are multi-channel audio signals. The reverberation applying unit generates the reverberant simulation signal on the basis of a signal obtained by synthesizing a part or all of the multi-channel audio signals.
Specifically, when sounds are outputted from the speakers which are provided around a user and to which multi-channel audio signals are supplied, it may occur that the user feels unbalance of surrounding indirect sounds in the sounds, for example, the user feels that there is a speaker which is disposed in the direction having a low reverberation. In this case, since the direction having the low reverberation may be substantially prominent, a surrounding effect of the multi-channel sounds may not be obtained. In the invention, since the output balance of the reverberation simulation signal is adjusted, the surrounding effect may be substantially exhibited.
According to the present invention, there is also provided a sound field controlling device comprising:
a direct supply unit which supplies an inputted audio signal to a speaker;
a measuring unit which measures a frequency characteristic of a sound when the sound outputted from the speaker arrives at a listening position;
a reverberation applying unit which generates a reverberation sound of the audio signal; and
a filter which filters the reverberation sound with a filter characteristic of compensating for a part or all of the measured frequency characteristic to supply the filtered reverberation sound to the speaker.
In the invention, the reverberation applying unit generates the reverberation sound of the audio signals, and the reverberation sound is filtered with the filter characteristic of compensating for a part or all of the frequency characteristic of the sound which is reached to the listening position from the speaker. Accordingly, when the frequency characteristic of the sound transmitted from the speaker to the listening position is not flat, the frequency characteristic of the reverberation sound is adjusted. Accordingly, a feeling of lack in the frequency characteristic of the sound field in which the sound system is installed is supplemented, and an unpleasant sound and a unnatural sound by a peak of the frequency characteristic of the direct sound component may be suppressed so as to generate the sound more smoothly.
Preferably, the direct supply unit supplies inputted multi-channel audio signals to different speakers respectively. The measuring unit and the filter are provided as many as the number of the channels of the multi-channel audio signals.
In the invention, the frequency characteristic at the time when sounds corresponding to the multi-channel audio signals arrive at the listening position from the speakers can be flat.
Preferably, the reverberation applying unit generates a reverberation simulation signal on the basis of a signal obtained by synthesizing a part or all of the multi-channel audio signals.
In the invention, the sound field is divided at every group of speakers, not divided at every speaker (for example, a front group of the speakers and a rear group of the speakers). Therefore, it is easy to control the sound field.
Preferably, the filter is set with the filter characteristic of compensating for a part of the measured frequency characteristic. The direct supply unit includes a direct sound filter which adjusts the frequency characteristic of the audio signal with the filter characteristic compensating for a part of the measured frequency characteristic.
In the invention, since the direct supply unit adjusts the frequency characteristic, the frequency characteristics of the direct sound and the indirect sound can be adjusted.
According to the invention, since unbalance of a reverberation in a space in which a speaker is installed and an unevenness of a frequency characteristic of sounds can be adjusted, a sound field having a good quality may be formed in a room where echoes of the sounds are different depending on directions in which the sounds are transmitted or where a specific frequency component of the sounds is absorbed.